Heart failure (HF) is a debilitating, end-stage disease in which abnormal function of the heart leads to inadequate blood flow to fulfill the needs of the body's tissues. Typically, the heart loses propulsive power because the cardiac muscle loses capacity to stretch and contract. Often, the ventricles do not adequately fill with blood between heartbeats, and the valves regulating blood flow may develop leaks, allowing regurgitation or backflow of blood. The impairment of arterial circulation deprives vital organs of oxygen and nutrients. Fatigue, weakness, and inability to carry out daily tasks may result. Not all HF patients suffer debilitating symptoms immediately. Some may live actively for years. Yet, with few exceptions, the disease is relentlessly progressive. As HF progresses, it tends to become increasingly difficult to manage.
Using temporary induced dyssynchrony (TID) therapy to create asynchrony in HF patients without underlying dyssynchrony has been shown to facilitate improvement of cardiac chamber function, cellular function, and cardiac reserve. Specifically, at least some known TID therapy, such as pacemaker-induced transient asynchrony (PITA) therapy that uses a pacemaker to induce asynchrony, involves using right ventricular (RV) pacing to induce forced ventricular asynchrony in a patient's heart at regular intervals (e.g., for a period of six hours every night for six weeks). One concept behind TID therapy is that the heart may benefit from “exercise” (i.e., forcing the heart into ventricular asynchrony), similar to other muscles in the body.
However, it has also been shown that TID therapy is effective when applied at regular, periodic intervals. When a patient is unable to tolerate a scheduled session of TID therapy and must cancel the session, the benefits of the TID therapy may be reduced. This may be of particular concern in patients experiencing atrial tachycardia, such as atrial fibrillation or atrial flutter. In such patients, the delivery of the TID therapy may need to be altered to achieve the desired benefits.